Prestige Red poinsettia (Euphorbia pulcherrima 'Prestige Red') has among the largest bracts of any of the poinsettia cultivars available this holiday season. It was rated among the best of the traditional red poinsettias in consumer preference tests conducted at Purdue University, North Carolina State University, and the University of Florida. Poinsettias have flower bracts that are often mistaken for flower petals but are actually modified leaves. The colors of the bracts are created through photoperiodism, meaning that they require darkness (12 hours at a time for at least five days in a row) to change color. At the same time, they require abundant light during the day for the brightest color. The flowers of the poinsettia, called cyathia, are unassuming, grouped within small yellow structures found in the center of each leaf bunch. Native to Mexico, the poinsettia derives its common English name from Joel Roberts Poinsett, the first United States minister to Mexico, who introduced the plant into this country in 1825. They contain an irritating milky sap common to most plants in the euphorbia family, but are not considered truly poisonous.